3 OPERATION AND APPLICATION
3.4 Manual operation
3.4.6 Switching the main screen view
The main screen, also called status page, with its set values, actual values and device status can be switched from the standard view mode with three or four values to a simpler mode which only shows two physical values.
The advantage of the alternative view mode is that actual values are displayed with bigger numbers, so they read be read from a larger distance. Refer to „3.4.3.8. Menu “HMI settings”“ to see where to switch the view mode in the MENU. Comparison:
Layout 1 (standard) Layout 2 (alternative)
Differences of layout 2:
• The two hidden physical values are shown when switching the knob assignment, which also changes the upper left half of the display
• The actual regulation mode is displayed no matter what pair of physical values is currently shown, in the lower left corner, as the example in the upper figure on the right side depicts with CR; this is the equivalent of layout 1 3.4.7 Switching the DC input on or off
The DC input of the device can be manually or remotely switched on and off. This can be restricted in manual operation by the control panel being locked.
Switching the DC input on during manual operation or digital remote control can be disabled by pin REM-SB of the optional analog interface, if installed and if the corresponding parameter is activated. For more information refer to 3.4.3.2 and example a) in 3.5.4.7. In such a situation, the device would show a notification in the display.
► How to manually switch the DC input on or off
1.
As long as the control panel (HMI) isn’t fully locked press the button . Otherwise you are asked to disable the HMI lock, either by simply pressing or entering the PIN, if the PIN has been activated in menu HMI Lock.2.
The ON/OFF button toggles between on and off, as long as a change isn’t restricted by any alarm or the device being in remote control. The DC input condition is indicated by the two LEDs (green = on, red = off)on the button.
► How to remotely switch the DC input on or off via the analog interface
1.
See section “„3.5.4 Remote control via the analog interface (AI)“ on page 36.► How to remotely switch the DC input on or off via the digital interface
1.
See the external documentation “Programming Guide ModBus & SCPI” if you are using custom software, or refer to the external documentation of LabView VIs or other documentation provided by EA Elektro-Automatik.3.5 Remote control
3.5.1 GeneralRemote control is possible via any of the optionally available, user-retrofittable interface cards (refer to „1.9.4.
Optional accessories“) and their feature analog or digital interface port. Important here is that only one of both ports can be in control. It means that if, for example, an attempt were to be made to switch to remote control via the digital interface whilst analog remote control is active (pin REMOTE = LOW) the device would report an error via the digital interface. In the opposite direction, a switch-over via pin REMOTE would be ignored. In both cases, however, status monitoring and reading of values are always possible.
3.5.2 Controls locations
Control locations are those locations from where the device is control. Essentially there are two: at the device (manual control) and external (remote control). The following locations are defined:
Displayed location Description
- If neither of the other locations is displayed then manual control is active and access from the analog and digital interfaces is allowed. This location isn’t explicitly displayed
Remote Remote control via any interface is active
Local Remote control is locked, only manual operation is allowed.
Remote control can be explicitly allowed or inhibited using the setting Allow remote control (see “„3.4.3.2. Menu
“General Settings”“). In inhibited condition, the status Local will be shown in the status area of the display. Activating the lock can be useful if the device is remotely controlled by software or some electronic device, but it’s required to make adjustments at the device or deal with emergency situations, which would not be possible remotely.
Activating condition Local causes the following:
• If remote control via the digital interface is active (shown as Remote:), then it’s immediately terminated and in order to continue remote control once Local is no longer active, it has to be reactivated from the PC side
• If remote control via the analog interface is active (Remote: Analog), then it’s temporarily interrupted until remote control is allowed again by deactivating Local, because pin REMOTE continues to signal “remote control = on”, unless the signal has been changed during the Local period.
3.5.3 Remote control via a digital interface 3.5.3.1 Selecting an interface
The device only supports the optionally available, digital interfaces USB and Ethernet.
For USB, a standard USB cable is included in the delivery of the interface card, not with the device, as well as a driver for Windows on USB stick. The USB interface requires no setup in the MENU.
The Ethernet interface typically requires network setup (manual or DHCP), but can also be used with its default parameters right from the start.
3.5.3.2 General
For the network port installation refer to „1.9.7. Ethernet port (optional)“.
The digital interface require little or no setup for operation and can be directly used with their default configura-tion. All specific settings will be permanently stored, but could also be reset to defaults with the setup menu item Reset Device.
Via the digital interface primarily the set values (voltage, current, power) and device conditions can be set and moni-tored. Furthermore, various other functions are supported as described in separate programming documentation.
Changing to remote control will retain the last set values for the device until these are changed. Thus a simple voltage control by setting a target value is possible without changing any other values.
3.5.3.3 Programming
Programming details for the interfaces, the communication protocols etc. are to be found in the documentation
“Programming Guide ModBus & SCPI“ which is supplied on the included USB stick or which is available as down-load from the EA Elektro-Automatik website.
3.5.4 Remote control via the analog interface (AI) 3.5.4.1 General
The optionally available, galvanically isolated, 15-pole analog interface (short: AI) is located on the rear side of the device and offers the following possibilities:
• Remote control of current, voltage, power and resistance
• Remote status monitoring (CC/CP, CV)
• Remote alarm monitoring (OT, OVP, PF)
• Remote monitoring of actual values
• Remote on/off switching of the DC input
Setting the set values of voltage, current and power via the analog interface must always be done concurrently.
It means, that for example the voltage can’t be given via the AI and current and power set by the rotary knobs, or vice versa. Using the resistance mode and can be switched on or off, so this signal isn’t always required.
Any device protection thresholds, such as OVP, can’t be set via the AI and therefore must be adapted to the given situation before the AI takes over control. Analog set values can be supplied by an external voltage source or generated from the reference voltage on pin 3. As soon as remote control via the analog interface is activated, the display will show the set values as provided on the analog interface.
The AI can be operated in the common voltage ranges 0...5 V and 0...10 V, both representing 0...100% of the nominal value. The selection of the voltage range can be done in the device setup. See section „3.4.3. Configura-tion via MENU“ for details. The reference voltage sent out from pin 3 (VREF) will be adapted accordingly:
0-5 V: Reference voltage = 5 V, 0...5 V set value signal for VSEL, CSEL and PSEL correspond to 0...100% nomi-nal value while for RSEL it’s RMIN...RMAX, 0...100% actual values correspond to 0...5 V at the actual value outputs CMON and VMON.
0-10 V: Reference voltage = 10 V, 0...10 V set value signal for VSEL, CSEL and PSEL correspond to 0...100%
nominal value while for RSEL it’s RMIN...RMAX, 0...100% actual values correspond to 0...10 V at the actual value outputs CMON and VMON.
All set values are always additionally limited to the corresponding adjustment limits (U-max, I-max etc.), which would clip setting excess values for the DC output. Also see section „3.4.4. Adjustment limits“.
Before you begin, please read these important notes for use of the interface:
After powering the device and during the start phase the AI signals undefined statuses on the output pins such as ALARMS or OVP. Those must be ignored until is ready to work.
• Analog remote control of the device must be activated by switching pin REMOTE first. Only exception is pin REM-SB, which can be used independently
• Before the hardware is connected that will control the analog interface, it shall be checked that it can’t provide voltage to the pins higher than specified
• Set value inputs, such as VSEL, CSEL, PSEL and RSEL (if R mode is activated), must not be left unconnected (i.e. floating) during analog remote control. In case any of these isn’t used for adjustment, it should be tied to a defined level like ground or connected to pin VREF (solder bridge or different), so it gives 100%
3.5.4.2 Resolution
The analog interface is internally sampled and processed by a digital microcontroller. This causes a specific effec-tive resolution, i. e. analog steps. The resolution is the same for set values (VSEL etc.) and actual values (VMON/
CMON) and is 4096 when working with the 10 V range. In the 5 V range this resolution halves. Due to tolerances, the truly achievable resolution can be slightly lower.
3.5.4.3 Acknowledging device alarms
Device alarms (see 3.6.1) are always indicated in the front display and some of them are also reported as signal on the analog interface socket (see table below).
In case of a device alarm occurring during remote control via analog interface, the DC input will be switched off the same way as in manual control. While alarms like OT (overtemperature), PF (power fail) and OV (overvoltage) can be monitored via the corresponding pins of the interface, other alarms like overcurrent (OC) can’t. Those could only be detected via the actual values of voltage and current being all zero contrary to the set values.
Some device alarms (OV, OC and OP) have to be acknowledged, either by the user of the device or by the control-ling unit. Also see „3.6.1. Device alarm and event handcontrol-ling“. Acknowledgement is done with pin REM-SB switching the DC input off and on again, means a HIGH-LOW-HIGH edge (at least 50 ms for LOW).
3.5.4.4 Analog interface specification
Pin Name Type* Description Default levels Electrical specification 1 VSEL AI Set voltage value 0…10 V or. 0...5 V
corre-spond to 0..100% of UNom Accuracy 0-5 V range: < 0.4% *****
Accuracy 0-10 V range: < 0.2% *****
Input impedance Ri >40 k...100 k 2 CSEL AI Set current value 0…10 V or. 0...5 V
corre-spond to 0..100% of INom
3 VREF AO Reference voltage 10 V or 5 V Tolerance < 0.2% at Imax = +5 mA Short-circuit-proof against AGND 4 DGND POT Ground for all digital signals For control and status signals 5 REMOTE DI Switching manual /
remote control
Remote = LOW, ULow <1 V Manual = HIGH, UHigh >4 V Manual, if not connected
Voltage range = 0…30 V IMax = -1 mA at 5 V ULOW to HIGH typ. = 3 V
Rec’d sender: Open collector against DGND
6 ALARMS DO Overheating alarm Power fail alarm ***
Alarm = HIGH, UHigh > 4 V No alarm = LOW, ULow <1 V
Quasi open collector with pull-up against Vcc **
With 5 V on the pin max. flow +1 mA IMax = -10 mA at UCE = 0,3 V
UMax = 30 V
Short-circuit-proof against DGND 7 RSEL AI Set internal
resist-ance value 0…10 V or. 0...5 V
corre-spond to 0..100% of RMax Accuracy 0-5 V range: < 0.4% *****
Accuracy 0-10 V range: < 0.2% *****
Input impedance Ri >40 k...100 k 8 PSEL AI Set power value 0…10 V or. 0...5 V
corre-spond to 0..100% of PNom
9 VMON AO Actual voltage 0…10 V or. 0...5 V corre-spond to 0..100% of UNom
Accuracy 0-5 V range: < 0.4% *****
Accuracy 0-10 V range: < 0.2% *****
at IMax = +2 mA
Short-circuit-proof against AGND 10 CMON AO Actual current 0…10 V or. 0...5 V
corre-spond to 0..100% of INom
11 AGND POT Ground for all analog signals For -SEL, -MON, VREF signals 12 R-ACTIVE DI R mode on / off Off = LOW, ULow <1 V
On = HIGH, UHigh >4 V On, if not connected
Voltage range = 0…30 V IMax = -1 mA at 5 V ULOW to HIGH typ. = 3 V
Rec’d sender: Open collector against DGND 13 REM-SB DI DC input OFF
(DC input ON) (ACK alarms ****)
Off = LOW, ULow <1 V On = HIGH, UHigh >4 V On, if not connected
Voltage range = 0…30 V IMax = +1 mA at 5 V
Rec’d sender: Open collector against DGND 14 OVP DO Overvoltage alarm Alarm = HIGH, UHigh > 4 V
No alarm = LOW, ULow <1 V Quasi open collector with pull-up against Vcc **
With 5 V on the pin max. flow +1 mA IMax = -10 mA at UCE = 0,3 V, UMax = 30 V Short-circuit-proof against DGND 15 CV DO Constant voltage
regulation active CV = LOW, ULow <1 V CC/CP/CR = HIGH, UHigh >4 V
* AI = Analog Input, AO = Analog Output, DI = Digital Input, DO = Digital Output, POT = Potential
** Internal Vcc approx. 10 V
*** AC supply blackout or PFC failure or supply undervoltage
**** Only during remote control
***** The error of a set value input adds to the general error of the related value on the DC input of the device
3.5.4.5 Overview of the Sub-D Socket
3.5.4.6 Simplified diagram of the pins
++ Digital Input (DI)
It requires to use a switch with low resist-ance (relay, switch, circuit breaker etc.) in order to send a clean signal to the DGND.
V~0.5
AGND
Analog Input (AI)
High resistance input (impedance
>40 k....100 kΩ) for an operational amplifier circuit.
4K7
+10V 12V Digital Output (DO)
A quasi open collector, realised as high resistance pull-up against the internal sup-ply. In condition LOW it can carry no load, merely switch, as shown in the diagram with a relay as example.
V~2
AGND
Analog Output (AO)
Output from an operational amplifier circuit, with low impedance. See specifications table above.
3.5.4.7 Application examples
a) Switching the DC input off or on via the pin REM-SB
A digital output, e.g. from a PLC, may be unable to cleanly effect this as it may not be of low enough resistance. Check the specification of the control-ling application. Also see pin diagrams above.
In remote control, pin REM-SB is used to switch the DC input of the device on and off. This is also available without remote control being active.
It is recommended that a low resistance contact such as a switch, relay or transistor is used to switch the pin to ground (DGND).
Following situations can occur:
• Remote control has been activated
During remote control via analog interface, only pin REM-SB determines the states of the DC input, according to the levels definitions in 3.5.4.4. The logical function and the default levels can be inverted by a parameter in the setup menu of the device. See 3.4.3.2.
If the pin is unconnected or the connected contact is open, the pin will be HIGH. With parameter
“Analog interface REM-SB” being set to “Normal”, it requests “DC input on”. In this situation, when activating remote control, the DC input would instantly switch on.
• Remote control isn’t active
In this mode of operation pin REM-SB can serve as lock, preventing the DC input from being switched on by any means. This results in following possible situations:
DC-input
+
Level on pin„REM-SB“+
Parameter„ A n a l o g interface REM-SB“ Behaviour
is off
+
HIGH+
Normal DC input not locked. It can be switched on by pushbutton On/Off (front panel) or via command from digital interface.LOW
+
Inverted+
HIGH+
Inverted DC input locked. It can’t be switched on by pushbutton On/Off (front panel) or via command from digital interface. When trying to switch on, a popup in the display resp. an error message will be generated.LOW
+
Normal HIGH
+
Normal DC input remains on, nothing is locked. It can be switched on or off by pushbutton or digital command.LOW
+
Inverted HIGH
+
Inverted DC input will be switched off and locked. Later it can be switched on again by toggling the pin. During lock, pushbutton or digital command can delete the request to switch on by pin.LOW
+
Normalb) Remote control of current and power.
Requires remote control to be activated (Pin REMOTE = LOW) The set values PSEL and CSEL are generated from, for exam-ple, the reference voltage VREF, using potentiometers for each.
Hence the electronic load can selectively work in current limiting or power limiting mode. According to the specification of max.
5 mA load for the VREF output, potentiometers of at least 10 kΩ must be used.
The voltage set value VSEL is directly connected to AGND (ground) and therefore has no influence on constant current or power operation.
If the control voltage is fed in from an external source it’s neces-sary to consider the input voltage ranges for set values (0...5 V or 0...10 V).
Use of the input voltage range 0...5 V for 0...100% set value halves the effective resolution.
Example with
The AI provides the DC input values as current and voltage monitor. These can be read using a standard multimeter or similar.
3.6 Alarms and monitoring
3.6.1 Device alarm and event handling Important to know:
• The current drained from a switching power supply or similar sources can be much higher than expected due to capacities on the source’s output, even if the source is current limited, and might thus trigger the overcurrent shutdown OCP of the electronic load, in case its threshold is adjusted too sensitively, it means too close to the related current set value
• When switching off the DC input of the electronic load while a current limited source still supplies energy, the output voltage of the source will rise immediately and due to response and settling times in effect, the output voltage can have an overshoot of unknown level which might trigger the overvoltage shutdown OVP, in case its threshold is adjusted too sensitively, it means too close to the related voltage set value
A device alarm incident will usually lead to DC input switch-off, the appearance of a text message in the display and, if activated, an acoustic signal to make the user aware. The alarm must always be acknowledged. If the alarm condition no longer exists, e.g. the de-vice has cooled down following overheating, the alarm indication may have disappeared already. If the condition persists, the display remains and the alarm can only be acknowl-edged after elimination of the cause.
► How to acknowledge an alarm in the display (during manual control)
1.
Once an alarm is indicated, the user can try to acknowledge and delete the alarm by pressing either buttonor .
In order to acknowledge an alarm during analog remote control, see „3.5.4.3. Acknowledging device alarms“. To acknowledge in digital remote, refer to the external documentation “Programming ModBus RTU & SCPI”.
Some device alarms are configurable:
Alarm Meaning Description Range Indication
OVP OverVoltage Protection
Triggers an alarm as soon as the DC input voltage reaches the defined threshold. The DC input will be
switched off. 0 V...1.03*UNom Display, analog &
digital interface
OCP OverCurrent Protection
Triggers an alarm as soon as the DC input current reaches the defined threshold. The DC input will be
switched off. 0 A....1.1*INom Display, digital
interface
OPP OverPower Protection
Triggers an alarm as soon as the DC input power reaches the defined threshold, The DC input will be
switched off. 0 W...1.1*PNom Display, digital
interface
These device alarms can’t be configured and are based on hardware:
Alarm Meaning Description Indication
PF Power Fail
PF Power Fail